EP 1 117 463 discloses a method of treating halogenous, organic waste material. The halogenous, organic waste material is decomposed by means of hydrolytic heating of a suspension of the waste material in comminuted state in an aqueous medium in the presence of a base such as alkaline and/or alkaline earth metal hydroxide at a temperature of between 250 and 280° C. at a pressure sufficient to keep the water in a liquid state, in a period of time sufficient to convert substantially all organically bound halogen present into inorganic halides. The aqueous medium used in the hydrolysis has a water content ensuring that a sufficient portion of the base present and all of the halide salts obtained are in solution during the entire process of hydrolysis. After the hydrolytic decomposition the hydrolysate obtained is separated into a solid phase and a liquid phase, thereafter the solid phase is treated in a post-heating liberating recyclable organic compounds having a melting point below room temperature and a boiling point above room temperature.
The liquid phase of the hydrolysate includes various alcohols which may be evaporated, isolated and exploited. This leaves behind a solid-containing residue including calcium sulphate and other inorganic materials containing alkali and/or alkali earth halide, alkali and/or alkali earth hydroxide and compounds containing heavy metals. At the further treatment according to EP 1 117 463 the remainder is washed with water and filtrated. The filtrate is directed to a system for precipitation of heavy metals in which the heavy metals, being dissolved as salts, are precipitated by means of e.g. NaS or NaOH or in a corresponding conventional manner. After precipitation the industrial waste water used may be directed on to a biologic sewage treatment works, or it may be directed back in the process.
The liquid phase of the hydrolysate typically includes approx. 2.1 meq/liter (mol equivalents/liter) of alkaline and/or alkaline earth metal halide. When exemplified by a chlorine containing waste treated with NaOH as the base this corresponds to approx. 11% by weight of sodium chloride. After the above treatment the halide salt will be present in the process water and is emitted into nature sooner or later. Although, in areas with access to emission into the sea or similar salt water reservoirs, environmentally such an emission into nature is justifiable when diluted sufficiently with additional water, the emission and disposal of industrial waste water containing halide salt may be problematic in areas far from major salt water areas. Furthermore it is unsatisfactory that halide salts, being a valuable resource, are not exploited.
Thus in general it can be noted that the halogenous content of the treated organic waste according to EP 1 117 463 is converted in an advantageous manner into a aqueous solution of halide salts which, after biological purification, e.g. may be emitted into the sea without environmental hazards per se.
Nevertheless emission of the purified halide salt solution is to be considered less desirable as:                The biological purification implies a major dilution of the halide solution, and thus occupies a considerable capacity of the sewage treatment plant.        Emission is not always possible or permitted from recycling plants far from the sea.        The halide solution represents a resource which may be the basis of commercial recovery of halide salts.        
Processing and recycling of halide salts may be effected in a conventional process by means of multi-stage evaporation in vacuo. Obtaining a well-crystallising halide salt product, however, implies a high degree of purity with regard to certain critical components. For instance, traces of lead, typically found in PVC waste and thus also in the resulting halide solution, are absorbed quantitatively in the obtained salt and cause deformed crystals. Moreover lead is undesirable in salt in a number of applications.
It has now appeared that by means of a relatively simple treatment of the liquid phase or fraction of the hydrolysate, said fraction may be purified for obtaining a pure salt product in the form of a usable resource material. Thus a pure salt product meeting the requirements for the application as a road salt or a “vacuum salt” may be obtained from a hydrolysate containing a chloride salt such as calcium or sodium chloride originating from the treatment of pure PVC waste. At the treatment of electronics scrap the hydrolysate includes a mix of halides. In this case pure mixtures of the halide salts such as CaF2, CaCl2 and CaBr2 and/or NaF, NaCl and NaBr can be obtained by means of the treatment. As industrially pure salts, NaF is used at a considerable scale for the fluoration of drinking water while NaBr is applied in an aqueous solution as balance liquid used at oil and gas wells, and as a biocide. Furthermore both salts are fine chemicals in a number of different connections. A mix of pure halide salts with CaBr2 and/or NaBr being the main components, as it is obtained by means of the treatment of electronics scrap, may replace CaBr2 and/or NaBr as a balance liquid in the oil industry. Mixtures of CaCl2 and NaCl are especially usable as road salt.